Subsea pressure relief devices and methods

ABSTRACT

A device for relieving pressure in a subsea component comprises a housing including an inner cavity, an open end in fluid communication with the inner cavity, and a through bore extending from the inner cavity to an outer surface of the housing. In addition, the device comprises a connector coupled to the open end. The connector is configured to releasably engage a mating connector coupled to the subsea component. Further, the device comprises a burst disc assembly mounted to the housing within the through bore. The burst disc assembly is configured to rupture at a predetermined differential pressure between the inner cavity and the environment outside the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/493,752 filed Jun. 6, 2011, and entitled “Subsea PressureRelief Device,” which is hereby incorporated herein by reference in itsentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

1. Field of the Invention

The disclosure relates generally to systems and methods for managingover pressurization of subsea equipment. More particularly, thedisclosure relates to burst disc assemblies and methods of using suchassemblies to relieve excessive fluid pressure in subsea equipment suchas conduits, pipelines, and fluid containment devices.

2. Background of the Technology

In producing oil and gas from offshore wells, an offshore productionsystem includes flowing hydrocarbons from a subterranean formationthrough a production string to a wellhead at the sea floor. From thewellhead, hydrocarbons may flow into tubular risers that provide a fluidconduit from the wellhead to the surface, where the hydrocarbons andother fluids may be collected in a receiving facility located on aplatform or other vessel. Alternatively, intermediate components may beconnected between the wellhead and risers, such as a choke/killmanifold, containment disposal manifold, capping stack, or other varioustypes of subsea equipment. At times, temporary flow lines from thewellhead to a receiving facility or other containment target, such as anexisting reservoir, may be installed.

The transfer of fluids from the wellhead to a receiving facility orother containment target often involves flow from a high pressure systemto a relatively low pressure system. Normally, the flow of hydrocarbonsfrom a subsea formation is controlled by a primary pressure containmentsystem, such as a series of valves installed on the wellhead, risers,and the receiving facility at the surface designed to withstandanticipated operating pressures emanating from the wellhead. However,such pressures may be erratic, resulting in unanticipated high fluidpressures entering the production system and possibly over pressurizingcomponents of the pressure containment system.

For instance, offshore oil production may take place at depths thousandsof feet below the surface, where the ambient water pressure may exceedseveral thousand pounds per square inch (PSI) at temperatures below 50°F. Such pressure and temperature conditions lead to the formation ofhydrocarbon gas hydrates, which may enter the production system. As thehydrates flow up the riser towards the surface, decreasing pressurewithin the riser at shallower depths allows the hydrates to disassociateinto water and gas and rapidly expand, violently ejecting fluid from theriser at the surface. Moreover, back pressure within the pressurecontainment system may be generated by closing valves or from otherprocesses, which may lead to an over pressurization of equipment in thesystem. In all such instances, it may be important to prevent pressurefrom building up in any interconnecting flow lines. Such an imbalance ofpressures could also build up due to hydrate formation, sudden pressurechanges in the well bore, or back pressure from valve closings or otherprocesses performed on the system.

Many primary pressure containment systems are active in nature,requiring operator monitoring and intervention, and the use ofhydraulic, electrical, or acoustic signals to activate the system in thecase of an unanticipated over pressurization. The reliance on operatorintervention may be problematic in certain situations, such as wheninclement weather due to a tropical storm or hurricane forces theevacuation of a production platform, limiting the ability of operatorsto monitor and manage any unanticipated pressurizations.

Further, because of the immense depths and associated hydrostaticpressures, effectuating repairs of subsea equipment in the productionsystem often requires that equipment and tools be handled by deepdiving, remotely operated vehicles (ROVs). Due to the need for ROVs,repairing or replacing subsea equipment damaged by an unanticipated overpressurization may be cumbersome, time consuming and expensive. Thus, inthe case of an unanticipated over pressurization, in order to reducecosts and quicken the time frame of repair it is necessary to ensurethat the amount of subsea equipment damaged by the over pressurizationis minimized and may be quickly and easily isolated and replaced.

Accordingly, there remains a need in the art for devices and methods formanaging unanticipated excessive pressurizations of subsea environment.Such devices and methods would be particularly well received if thepressure setting at which the pressure relief device operates could beeasily adjusted. Further, it would be advantageous if the pressurerelief device could act passively, not requiring operator monitoring andactuation or the input of any hydraulic, electrical, or acoustic signalfor actuation. Still further, it would be advantageous if the pressurerelief device could be retrieved and replaced with relative ease.

BRIEF SUMMARY OF THE DISCLOSURE

These and other needs in the art are addressed in one embodiment by adevice for relieving pressure in a subsea component. In an embodiment,the device comprises a housing including an inner cavity, an open end influid communication with the inner cavity, and a through bore extendingfrom the inner cavity to an outer surface of the housing. In addition,the device comprises a connector coupled to the open end. The connectoris configured to releasably engage a mating connector coupled to thesubsea component. Further, the device comprises a burst disc assemblymounted to the housing within the through bore. The burst disc assemblyis configured to rupture at a predetermined differential pressurebetween the inner cavity and the environment outside the housing.

These and other needs in the art are addressed in another embodiment bya method for relieving pressure within a subsea conduit. In anembodiment, the method comprises (a) deploying a pressure relief devicesubsea. The pressure relief device includes a housing having an innercavity and a through bore extending from the inner cavity to an outersurface of the housing, and a burst disc assembly mounted to the housingwithin the through bore. In addition, the method comprises (b) couplingthe pressure relief device to the subsea conduit. Further, the methodcomprises (c) transferring fluid pressure from the subsea conduit to theinner cavity.

These and other needs in the art are addressed in another embodiment bya device for relieving pressure in a subsea fluid conduit. In anembodiment, the device comprises a manifold including an inlet end and aplurality of outlet ends. In addition, the device comprises a connectorcoupled to the inlet end of the manifold. The connector is configured toreleasably engage a mating connector coupled to the fluid conduit.Further, the device comprises a plurality of valve spools. Each valvespool is coupled to one of the outlet ends of the manifold. Each valvespool includes a valve configure to control a flow of fluids through thecorresponding valve spool. Still further, the device comprises aplurality of burst disc assemblies. One burst disc assembly is disposedin a through bore in each valve spool. Each burst disc assembly isconfigured to rupture at a predetermined differential pressure betweenthe inner cavity and the environment outside the housing.

Embodiments described herein comprise a combination of features andadvantages intended to address various shortcomings associated withcertain prior devices, systems, and methods. The various characteristicsdescribed above, as well as other features, will be readily apparent tothose skilled in the art upon reading the following detaileddescription, and by referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the apparatus, systems and methodsdisclosed herein, reference will now be made to the accompanyingdrawings in which:

FIG. 1 is a schematic view of an offshore hydrocarbon production system;

FIG. 2 is an isometric view of the containment and disposal manifoldassembly of FIG. 1 including an embodiment of a pressure relief devicein accordance with the principles described herein;

FIG. 3 is a side view of the containment and disposal manifold assemblyof FIG. 2;

FIG. 4 is an isometric view of the pressure relief device of FIG. 2;

FIG. 5 is a side view of the pressure relief device of FIG. 4;

FIG. 6 is a cross-sectional view of the pressure relief device of FIG.4;

FIG. 7A is a cross-sectional view of one of the burst disc assemblies ofFIG. 4;

FIG. 7B is a top view of one of the burst disc assemblies of FIG. 4;

FIG. 8 is a schematic view of the upper riser assembly and lower riserassembly of the free standing riser of FIG. 1;

FIG. 9 is an isometric view of the pressure relief device coupled to thelower riser assembly of FIG. 8;

FIG. 10 is a side view of the pressure relief device of FIG. 9;

FIG. 11 is a cross-sectional view of the pressure relief device of FIG.9;

FIG. 12 is a schematic cross-sectional view of the pressure reliefdevice coupled to the upper riser assembly of FIG. 8; and

FIG. 13 is a schematic view of an embodiment of a pressure relief devicein accordance with the principles described herein.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following discussion is directed to various exemplary embodiments.However, one skilled in the art will understand that the examplesdisclosed herein have broad application, and that the discussion of anyembodiment is meant only to be exemplary of that embodiment, and notintended to suggest that the scope of the disclosure, including theclaims, is limited to that embodiment.

Certain terms are used throughout the following description and claimsto refer to particular features or components. As one skilled in the artwill appreciate, different persons may refer to the same feature orcomponent by different names. This document does not intend todistinguish between components or features that differ in name but notfunction. The drawing figures are not necessarily to scale. Certainfeatures and components herein may be shown exaggerated in scale or insomewhat schematic form and some details of conventional elements maynot be shown in interest of clarity and conciseness.

In the following discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . .” Also, theterm “couple” or “couples” is intended to mean either an indirect ordirect connection. Thus, if a first device couples to a second device,that connection may be through a direct connection, or through anindirect connection via other devices, components, and connections. Inaddition, as used herein, the terms “axial” and “axially” generally meanalong or parallel to a central axis (e.g., central axis of a body or aport), while the terms “radial” and “radially” generally meanperpendicular to the central axis. For instance, an axial distancerefers to a distance measured along or parallel to the central axis, anda radial distance means a distance measured perpendicular to the centralaxis.

A subsea pressure relief or control system for subsea applications isdisclosed herein. Embodiments described herein may be employed invarious subsea applications; however, it has particular application as adevice to relieve excessive fluid pressures that may develop in subseaflow lines, manifolds, tanks, vessels and reservoirs containing and/ortransporting hydrocarbons from the sea floor or between subseacontainment systems.

Referring now to FIG. 1, an overview of an offshore hydrocarbonproduction system 100 is shown. In this embodiment, system 100 comprisesa blowout preventer (BOP) 130 mounted to a subsea wellhead, a choke/killmanifold assembly 140 disposed on the sea floor 120, a plurality ofprocessing vessels 170 and collecting vessels 180 disposed at the seasurface 110, a containment and disposal manifold assembly 200 disposedon sea floor 120, and a plurality of subsea free standing risers (FSRs)600.

Each FSR 600 is vertically oriented and has a first or upper end 600 aand a second or lower end 600 b. In this embodiment, each FSR 600includes a buoyancy can 166 at upper end 600 a, an upper riser assembly(URA) 610 coupled to can 166, a foundation 168 at lower end 600 b, and alower riser assembly (LRA) 620 coupled to foundation 168. Foundations168 secure FSRs 600 to the sea floor 120, and buoyancy cans 166 placeFSRs 600 in tension. URAs 610 of each FSR 600 are disposed below thewave zone proximal the sea surface 110, thereby minimizing lateral andradial loads applied to FSRs 600. As will be described in more detailbelow, an embodiment of a subsea pressure relief device in accordancewith principles described herein is included in LRA 620 and URA 610 ofeach FSR 600 to protect such components from over pressurization.

Processing vessels 170 are coupled to URAs 610 of each FSR 600 by aplurality of flexible jumpers 104. In addition, a fluid conduit 108couples each vessel 170 to a corresponding vessel 180.

In this embodiment, a capping stack 131 is coupled to BOP 130. Examplesof capping stacks are disclosed in U.S. provisional patent applicationSer. No. 61/475,032 filed Apr. 13, 2011, and entitled “Systems andMethods for Capping a Subsea Well,” which is hereby incorporated here inreference in its entirety. Choke/kill manifold assembly 140 is coupledto BOP 130, and a drill string 106 and containment and disposal manifoldassembly 200 are coupled to choke/kill manifold assembly 140 by subseaconduits 102. As will be described in more detail below, containment anddisposal manifold assembly 200 provides additional protection during anover pressurization. As will be described in more detail below, anembodiment of a subsea pressure relief device in accordance withprinciples described herein is included in containment and disposalmanifold assembly 200.

The offshore hydrocarbon production system 100 may be further explainedin provisional application Nos. 61/392,443 and 61/392,899. Provisionalapplication No. 61/392,443 and provisional application No. 61/392,899are incorporated by reference in their entirety, for all purposes.

Referring now to FIGS. 2 and 3, containment and disposal manifoldassembly 200 is shown. Manifold assembly 200 includes a base 210, asupport frame 220, a manifold 230, an ROV panel 260, and a pressurerelief device 400. Base 210 distributes the weight of manifold assembly200 along the sea floor 120, thereby restricting and/or preventingmanifold assembly 200 from sinking into the sea floor 120. In addition,base 210 covers and shields the sea floor 120 from turbulence induced byROV thrusters, thereby reducing visibility loss due to disturbed mudduring installation and operation. Accordingly, base 210 effectivelyfunctions as a mud mat.

Support frame 220 sits atop base 210 and provides support for manifold230. Manifold 230 includes an arrangement of interconnected fluidconduits 238, a plurality of valves 232, and a plurality of verticalconnection conduits 234. Valves 232 are configured to control the flowof fluids through conduits 238, 234. For example, each valve 232 has anopen position allowing fluid flow therethrough and a closed positionrestricting and/or preventing fluid flow therethrough. One valve 232 isassociated with each conduit 234, thereby controlling fluidcommunication between that particular conduit 234 and the remainingconduits 238 of manifold 230. ROV panel 260 enables a subsea ROV toselectively and independently control valves 232. The upper end of eachconduit 234 includes a connector or hub 236 configured to mate andreleasably engage a mating connector. In this embodiment, pressurerelief device 400 is releasably coupled to one hub 236.

Referring now to FIGS. 4-6, pressure relief device 400 has a central orlongitudinal axis 405, a first or upper end 400 a, and a second or lowerend 400 b. In this embodiment, assembly 400 includes a connector 420 atlower end 400 b and a tubular housing 410 coupled to connector 420.

As best shown in FIG. 6, tubular housing 410 is coaxially aligned withaxis 405, and has a first or upper end 410 a coincident with end 400 a,a second or lower end 410 b connected to connector 420, a radially innersurface 418, and a radially outer surface 419 Inner surface 418 definesan inner cavity 416 extending axially between ends 410 a, b. Tubularhousing 410 also includes a plurality of axially spaced radial bores 417extending radially between surfaces 418, 419. One burst disc assembly500 is mounted within each bore 417. In this embodiment, a plurality oflugs or lift eyes 414 extend from outer surface 419 and are used to liftand deploy assembly 400.

A cap 430 is mounted to upper end 410 a of tubular housing 410, therebygenerally closing upper end 410 a. Cap 430 includes a through bore 432in fluid communication with cavity 416 of tubular housing 410. The upperend of bore 432 includes a receptacle 435 coupled to a conduit 448 thatextends to a hot stab receptacle 442 in an ROV panel 446 mounted totubular housing 410. A valve 444 in panel 446 controls fluidcommunication between conduit 448 and receptacle 442. Namely, valve 444has an open position allowing fluid communication between conduit 448and receptacle 442, and a closed position restricting and/or preventingfluid communication between conduit 448 and receptacle 442.

During subsea operations, receptacle 442 and conduit 448 can be used toeither inject chemicals into tubular housing 410 or to receivehydrocarbons from housing 410. For example, a subsea ROV may insert ahot stab connector into receptacle 442, open valve 444, and inject ahydrate inhibitor (e.g., methanol) into tubular housing 410. Receptacle442 and conduit 448 may also be used to inject dispersant into tubularhousing 410 through conduit 448 in the event of the rupturing of burstdisk assemblies 500. Further, samples of fluid within tubular housing410 may be taken by flowing fluid from housing 410 through conduit 448and into a hot stab connector coupled to receptacle 442. Receptacle 442and conduit 448 may also be used to displace fluid within tubularhousing 410 and manifold 230. For instance, a relatively less densefluid, such as methanol, may be injected into manifold 230 throughconduit 448 and tubular housing 410 in order to displace hydrocarbonsout of housing 410 and manifold 230. Alternatively, a relatively highdensity fluid, such as glycol, may be inputted into tubular member 410from manifold 230, displacing hydrocarbons from within member 410through conduit 448 and into a hot stab connector coupled to receptacle442.

Connector 420 is coaxially aligned with tubular housing 410 and includesa female receptacle 428 at lower end 400 b and an internal passage 425extending axially from receptacle 428 to cavity 416 of tubular housing410. Thus, passage 425 and cavity 416 are in fluid communication.Connector 420 is configured to releasably connect with manifold hub 236previously described. In particular, hub 236 is received, seated, andreleasably locked within female receptacle 428 of connector 420, therebyproviding fluid communication between passages 425, 416 and conduit 234of manifold 230. Connector 420 also includes a plurality ofcircumferentially spaced vertical indicator pins 422 as are known in theart. Indicator pins 422 provide a visual indication of the configurationof connector 420. Namely, when pins 422 are axially extended fromconnector 420 as shown in FIGS. 4-6, connector 420 is in an unlockedposition (e.g., connector 420 is not locked onto mating hub 236;however, when pins 422 are retracted into connector 420, connector 420is in a locked position (e.g., connector 420 is locked onto mating hub236). In this embodiment, connector 420 is a hydraulically actuatedcollet connector, such as a 3″ mini CVC connector, made by CameronInternational Corporation of Houston, Texas. In other embodiments,connector 420 may be an Optima™ subsea connector made by VectorTechnology Group of Drammen, Norway, or other connectors of the likeknown in the art.

As best seen in FIGS. 4 and 5, ROV panel 450 is coupled to connector 420and enables a subsea ROV to actuate connector 420 between the locked andunlocked positions. In this embodiment, panel 450 includes a hot stabreceptacle 452 and a valve 454 that controls the flow of fluids fromreceptacle 452 to connector 420. For example, an ROV can actuateconnector 420 by opening a valve 454 and inputting hydraulic power toconnector 420 via a hot stab receptacle 454.

Referring now to FIGS. 7A and 7B, one burst disc assembly 500 is shown.Burst disc assembly 500 has a central axis 560 and includes a radiallyouter annular body or housing 510 sized to fit within a correspondingbore 417 in tubular housing 410, and an annular burst disc 540 disposedwithin housing 510. Disc 540 has a concave outer surface 542 facing theambient environment surrounding assembly 400, and a convex inner surface544 facing cavity 416. Disc 540 is configured to be forcibly pushedaxially out of housing 510 at a predetermined differential pressurethereacross. Thus, when one or more burst disc assembly 500 ruptures,cavity 416 of tubular housing 410 is placed in fluid communication withthe surrounding environment, thereby relieving pressure within assembly400 as well as other components in fluid communication with assembly400. In this embodiment, each of the plurality of burst disc assemblies500 in assembly 400 is configured to rupture at the same differentialpressure between cavity 416 and the outside environment. In general,burst disc assemblies 500 may comprise any suitable passive devicedesigned to rupture at a predetermined pressure differential. Examplesof suitable burst discs are burst discs manufactured by the FikeCorporation of Blue Springs, Mo.

Referring now to FIGS. 2, 5 and 6, in the event of an overpressurization of manifold 230, the high fluid pressure seen by manifold230 is transmitted through vertical connection conduit 234 and connector420 into cavity 416 of tubular housing 410. The increased fluid pressurewithin cavity 416 results in a larger differential pressure across burstdisc assemblies 500 (i.e., a larger pressure differential between cavity416 and the outside ambient environment). Upon the reaching of apredetermined pressure differential, one or more discs 540 are forcedradially outward from the corresponding housing(s) 510, thereby placingcavity 416 and manifold 230 into fluid communication with the ambientenvironment and relieving pressure therewithin.

Once discs 540 have been expelled and hydrostatic pressure hassufficiently decreased within manifold 230 (i.e., to a level at whichdamage from over pressurization is no longer of concern), valve 232 canbe actuated into its closed position via an ROV, thereby restrictingand/or preventing further flow of fluids from manifold 230 to verticalconnection conduit 234 and assembly 400. At this point, assembly 400 maybe disconnected from manifold 230 at connector 420 and lifted to thesurface via a cable attached to lift eyes 414. With assembly 400removed, a new assembly 400, including intact burst disc assemblies 500,is coupled to manifold 230 at connector 420, thereby replacing theprevious assembly 400. Upon coupling new assembly 400 and manifold 230,valve 232 is actuated into its open position, establishing fluidcommunication between new assembly 400 and manifold 230.

Referring now to FIG. 8, a schematic view of FSR 600, including URA 610and LRA 620, is shown. In this embodiment, a pressure relief device 700is removably coupled to LRA 620 and a pressure relief device 800 isremovably coupled to URA 610. In particular, fluid conduits 602, 604 arecoupled to LRA 620 and URA 610, respectively. Conduit 602 is in fluidcommunication with LRA 620 and has an inlet end 602 a connected to LRA620, an outlet end 602 b releasably coupled to pressure relief device700, and a valve 622 disposed between ends 602 a, b. Pressure reliefdevice 700 is removably coupled to end 602 b. In particular, end 602 bcomprises a connector configured to mate and releasably engage a matingconnector 710 of pressure relief device 700. Valve 622 controls the flowof fluids between ends 602 a, b. Namely, valve 622 has an open positionallowing fluid communication between ends 602 a, b and a closed positionrestricting and/or preventing fluid communication between ends 602 a, b.

Conduit 604 is in fluid communication with URA 610 and has an inlet end604 a connected to URA 610, an outlet end 604 b releasably coupled topressure relief device 800, and a pair of valves 612 disposed betweenends 604 a, b. Pressure relief device 800 is removably coupled to end604 b. In particular, end 604 b comprises a hot stab receptacle 810configured to mate and releasably engage a mating hot stab 810 ofpressure relief device 800. Valves 612 control the flow of fluidsbetween ends 604 a, b. Namely, each valve 612 has an open positionallowing fluid communication therethrough and a closed positionrestricting and/or preventing fluid communication therethrough. Thus, ifone or both valves 612 are closed, fluid communication between ends 604a, b is restricted and/or prevented.

Referring now to FIGS. 9-11, pressure relief device 700 has a central orlongitudinal axis 705, a first or upper end 700 a, and a second or lowerend 700 b. In this embodiment, assembly 700 includes connector 710 atend 700 b, a tubular member 720, a burst disc housing 730 at end 700 a,and a plurality of burst disc assemblies 500 as previously describedmounted to housing 730. As best shown in FIG. 11, connector 710 has aradially outer surface including an annular flange 714 and a radiallyinner surface defining a through bore 712. In this embodiment, connector710 is the female end of a vice connector, such as an Optima SubseaConnector, made by Vector Technology Group of Drammen, Norway. Tubularmember 720 extends axially between connector 710 and housing 730 andincludes an inner through bore 724 in fluid communication with bore 712of connector 710.

Housing 730 is disposed at upper end 700 a and includes an inner cavity735 in fluid communication with bore 724 and a plurality of bores 732extending radially through housing 730 from cavity 735 to the outersurface of housing 730. Each bore 732 includes an inner annular shoulder736. One burst disc assembly 500 is coaxially disposed within each bore732 and seated against the corresponding shoulder 736. A tubularretention member 742 is threaded into each bore 732 followinginstallation of the corresponding burst disc assembly 500 to maintainthe position of burst disc assembly 500 seated against shoulder 736.Retention member 742 engages housing 510 of burst disc assembly 500, butdoes not engage disc 540. In particular, retention member 742 has aninner diameter greater than the diameter of disc 540, and thus, disc 540can be forced radially outward through retention member 742. Aspreviously described, disc 540 is configured to be forcibly pushedaxially out of housing 510 at a predetermined differential pressurethereacross. Thus, at a predetermined differential pressure betweencavity 735 and the outside ambient environment, disc 540 is forcedradially outward from housing 510 through retention member 742, therebyrelieving fluid pressure within assembly 700. As best seen in FIGS. 9and 10, a lug or lifting ring 733 and an ROV handle 731 are coupled tohousing 730 and facilitate the subsea installation and removal ofassembly 700.

Referring now to FIGS. 8 and 11, in the event of an over pressurizationof LRA 620, the relatively high hydrostatic pressure seen by LRA 620 istransmitted through conduit 602, valve 622, and connector 710 intoassembly 700. The increased hydrostatic pressure within cavity 735results in a larger differential pressure across burst disc assemblies500. At a predetermined differential pressure, disc 540 is forciblycompelled radially from housing 510 through retention member 742,thereby placing cavity 735 and LRA 620 in fluid communication with thesurrounding ambient environment and relieving fluid pressure therein.

Once disc 540 has been expelled and pressure has decreased within LRA620, valve 622 may be actuated into its closed position via an ROV,thereby restricting and/or preventing fluid flow from LRA 620 toconnector 710. At this point assembly 700 is disconnected from LRA 620at connector 710 and lifted to the surface via a cable attached tolifting ring 733. Once assembly 700 has been removed, another assembly700 is coupled to LRA 620 at connector 710. Valve 622 is then opened,establishing fluid communication between new assembly 700 and LRA 620.

Referring now to FIGS. 8 and 12, pressure relief device 800 has acentral or longitudinal axis 805, a first end 800 a, and a second end800 b opposite end 800 a. In this embodiment, assembly 800 comprises astabbing member 820 extending axially from end 800 a, a burst dischousing 830 coupled to stabbing member 820, and a burst disc assembly500 mounted to housing 830 at end 800 b. Stabbing member 820 iscoaxially aligned with housing 830 and has a first end 820 a coincidentwith end 800 a and a second end 820 b opposite end 820 a. End 820 a isconfigured to be inserted and axially advanced into receptacle 810, andend 820 b comprises an internally threaded receptacle 824 that receiveshousing 830. An inner axial flow passage 821 extends through stabbingmember 820 from proximal end 820 a to receptacle 824, and a port 822extends radially from passage 821 to the outer surface of member 820.

Member 820 is configured to be coaxially inserted into and removablyseated within mating receptacle 810. A plurality of annular sealassemblies 828 are disposed about stabbing member 820 to seal betweenmember 820 and receptacle 810. In this embodiment, each seal assembly828 includes an annular recess or seal gland in the outer surface ofstabbing member 820 and an annular seal member (e.g., O-ring seal)seated in the gland. In general, stabbing member 820 may comprise anysuitable member configured to be inserted into and releasably engagedwith receptacle 810. In this embodiment, stabbing member 820 is a 2″Subsea Stab, produced by NLI Asker Subsea of Lier, Norway. With stabbingmember 820 seated in receptacle 810, port 822 is aligned with a matingport 813 in receptacle 810, thereby placing flow passage 821 in fluidcommunication with conduit 604, which is in selective fluidcommunication with URA 610 of FSR 600. A handle 826 is attached tostabbing member 820 and is configured to allow a subsea ROV to positionand manipulate assembly 800.

Referring still to FIG. 12, housing 830 has a first end 830 a, a secondend 830 b opposite end 830 a, an inner cavity 834 at end 830 b, and aflow bore 833 extending axially from end 830 a to cavity 834. Inaddition, housing 830 includes a cylindrical connection portion 831extending axially from end 830 a and a burst disc mounting portion 832extending axially from portion 831 to end 830 b. Passage 833 extendsthrough connection portion 831 and cavity 834 is disposed withinmounting portion 832. Connection portion 831 is threaded into matingreceptacle 824. With housing 830 coupled to stabbing member 820, cavity834 and bore 833 are in fluid communication with passage 821 of stabbingmember 820. An annular seal assembly 837 is disposed about connectionportion 831 to seal between housing 830 and stabbing member 820. In thisembodiment, seal assembly 837 includes an annular recess or seal glandin the outer surface of connection portion 831 and an annular sealmember (e.g., O-ring seal) seated in the gland.

A burst disc assembly 500 as previously described is coaxially mountedin an aperture 835 in portion 832 at end 830 b. As previously described,disc 540 is configured to be forcibly pushed axially out of housing 510at a predetermined differential pressure thereacross. Thus, at apredetermined differential pressure between cavity 834 and the outsideambient environment, disc 540 is forced radially outward from housing510, thereby relieving fluid pressure within assembly 800.

In the event of an overpressurization of URA 610 of FSR 600, therelatively high fluid pressure within URA 610 is transmitted throughconduit 604, valves 612, port 813, and passages 822, 833 into cavity834. At a predetermined differential pressure, disc 540 is forciblycompelled radially from housing 510, thereby placing cavity 834 and URA610 in fluid communication with the surrounding ambient environment andrelieving fluid pressure therein.

Once disc 540 has been expelled and pressure has decreased within URA610, valves 612 may be actuated into their closed positions via an ROV,thereby restricting and/or preventing fluid flow from URA 610 toreceptacle 810. At this point assembly 800 is disconnected from URA 610and lifted to the surface. Once assembly 800 has been removed, anotherassembly 800 is coupled to URA 610 at receptacle 810. Valves 612 arethen opened, establishing fluid communication between new assembly 800and URA 610.

Now referring to FIG. 13, another embodiment of a burst disc assembly900 is schematically shown. Assembly 900 includes a connector 910, amain conduit 920 coupled to connector 910, a manifold 924 coupled toconduit 920, and a plurality of valve spools 926 coupled to manifold924. Conduit 920 has a central or longitudinal axis 925, a first orupper end 920 a, and a second or lower end 920 b. Connector 910 iscoupled to end 920 b and manifold 924 is coupled to end 920 a. Connector910 is configured to couple assembly 900 to a subsea component such ascontainment and disposal manifold assembly 200, URA 610 or LRA 620 ofFSR 600, or other locations within hydrocarbon production system 100 ofFIG. 1. In general, connector 910 may comprise any suitable connector ordevice for coupling assembly 900 to a subsea component such as a CameronCVC connector, as described above, or a Vector Optima™ connector, alsodescribed above.

Manifold 924 includes an inlet 924 a in fluid communication with conduit920 and a plurality of outlets 924 b, each outlet 924 in fluidcommunication with one valve spool 926. Thus, manifold 924 suppliesfluid from conduit 920 to valve spools 926.

Each valve spool 926 includes a valve 928 that controls the flow offluids therethrough, a plurality of circumferentially spaced radialthrough bores 417, and a plurality of burst disc assemblies 500 aspreviously described, one burst disc assembly 500 being mounted in eachbore 417. Each valve 928 has an open position that allows fluidcommunication between manifold 924 and the corresponding burst discassemblies 500, and a closed position restricting and/or preventingfluid communication between manifold 924 and the corresponding burstdisc assemblies 500.

A cap 430 as previously described is mounted to the upper end of eachspool 926 distal manifold 924. Receptacle 435 in each cap 430 is coupledto a conduit 448 connected to a hot stab receptacle 442 in an ROV panel446 mounted to conduit 920. A valve 444 is provided in panel 446 foreach conduit 448, each valve controlling fluid communication betweenconduit 448 and receptacle 442. During subsea operations, receptacle 442and conduit 448 may be used to inject chemicals into the correspondingvalve spool 926 or receive fluids from within valve spool 926 in themanner previously described above.

As previously described, each burst disc assembly 500 is configured torupture at a predetermined pressure differential. One or more burst discassemblies 500 may be configured to rupture at the same or differentpredetermined pressure differentials. For example, within each valvespool 926, burst disc assemblies 500 may be configured to rupture at thesame predetermined pressure differential, but between different valvesspools 926, burst disc assemblies 500 may be configured to rupture atdifferent predetermined pressures. Thus, for example, one spool 926 mayinclude burst disc assemblies 500 configured to burst at a lower orhigher differential pressure than the burst disc assemblies 500 of theother spools 926. In this example, the burst disc assemblies 500configured to rupture at the lowest predetermined pressure differentialwill rupture first, thereby partially relieving pressure within assembly900. Additional burst disc assemblies 500 may rupture until the pressureis sufficiently relieved. Any one or more valve spools 926 including aruptured burst disc assembly 500 may be isolated from manifold 924 bythe actuation of its respective valve 928 into the closed position.Spools 926 including burst disc assemblies 500 that have not rupturedcan be kept open to protect against future over pressurizations.

In the manner described herein, embodiments of devices and methodsdescribed herein provide passive protection against unanticipated overpressurization of subsea components. Although embodiments describedherein Such embodiments may be tailored to provide pressure relief at aparticular predetermined pressure differential between the fluid withinthe subsea component and the ambient environment outside the component,thereby enabling control over the pressure differential at whichpressure relief is triggered. In addition, embodiments described hereinenable control over the location at which pressure relief occurs,effectively sacrificing an easily replaced relatively low cost device(e.g., burst disc assembly) to reduce the potential for undesirablydamaging one or more other subsea components that may be more difficultto repair and/or replace. In general, embodiments of pressure reliefdevices, systems, and methods described herein may be used inconjunction with subsea fluid conduits, subsea containment vessels ordevices, or any other subsea component that flows or contains fluid.

Although embodiments of pressure relief devices (e.g., burst discassemblies) are shown and described in connection with upper riserassemblies, lower riser assemblies, and subsea manifolds, it should beappreciated that embodiments described herein can be used as pressurecontrol devices on a variety of other subsea conduits and components.For example, a pressure relief device can be connected to a cappingstack, BOP, fluid conduit, etc. Further, it should be appreciated thatembodiments described herein may be used in conjunction with othersubsea pressure relief systems and devices. Examples of other pressurerelief devices are described in U.S. provisional patent application Nos.61/481,976, 61/479,693, and 61/479,671, each of which is herebyincorporated herein by reference in its entirety for all purposes.

While specific embodiments have been shown and described, modificationsthereof can be made by one skilled in the art without departing from thescope or teachings herein. The embodiments described herein areexemplary only and are not limiting. Many variations and modificationsof the systems, apparatus, and processes described herein are possibleand are within the scope of the invention. For example, the relativedimensions of various parts, the materials from which the various partsare made, and other parameters can be varied. Accordingly, the scope ofprotection is not limited to the embodiments described herein, but isonly limited by the claims that follow, the scope of which shall includeall equivalents of the subject matter of the claims. Unless expresslystated otherwise, the steps in a method claim may be performed in anyorder. The recitation of identifiers such as (a), (b), (c) or (1), (2),(3) before steps in a method claim are not intended to and do notspecify a particular order to the steps, but rather are used to simplifysubsequent reference to such steps.

1. A device for relieving pressure in a subsea component, the devicecomprising: a housing including an inner cavity, an open end in fluidcommunication with the inner cavity, and a through bore extending fromthe inner cavity to an outer surface of the housing; a connector coupledto the open end, wherein the connector is configured to releasablyengage a mating connector coupled to the subsea component; and a burstdisc assembly mounted to the housing within the through bore, whereinthe burst disc assembly is configured to rupture at a predetermineddifferential pressure between the inner cavity and the environmentoutside the housing.
 2. The device of claim 1, wherein the connector isa hydraulically actuated collet connector.
 3. The device of claim 1,wherein the connector is a hot stab configured to releasably engage amating receptacle.
 4. The device of claim 1, further comprising aplurality of burst disc assemblies; wherein the housing includes aplurality of through bores, each through bore extending from the innercavity to the outer surface of the housing; wherein one burst discassembly is disposed in each through bore in the housing; wherein eachburst disc assembly is configured to rupture at a predetermineddifferential pressure between the inner cavity and the environmentoutside the housing.
 5. The device of claim 4, wherein each burst discassembly is configured to rupture at the same predetermined differentialpressure.
 6. The device of claim 1, further comprising a handle coupledto the housing, wherein the handle is configured to be grasped by asubsea ROV.
 7. The device of claim 1, wherein the housing is a tubularand has the open end and a closed end opposite the open end.
 8. Thedevice of claim 1, further comprising: a conduit having a first endcoupled to the housing and a second end coupled to a receptacle in anROV panel, wherein the conduit is in fluid communication with the innercavity; a valve configured to control fluid communication between theinner cavity and the receptacle.
 9. A method for relieving pressurewithin a subsea conduit, the method comprising: (a) deploying a pressurerelief device subsea, wherein the pressure relief device includes ahousing having an inner cavity and a through bore extending from theinner cavity to an outer surface of the housing, and a burst discassembly mounted to the housing within the through bore; (b) couplingthe pressure relief device to the subsea conduit; and (c) transferringfluid pressure from the subsea conduit to the inner cavity.
 10. Themethod of claim 9, further comprising: (d) closing a valve in the subseacomponent to restrict fluid communication between the subsea conduit andthe inner cavity.
 11. The method of claim 10, further comprising: (e)decoupling the pressure relief device from the subsea conduit.
 12. Themethod of claim 9, wherein the pressure relief device includes ahydraulically actuated collet connector coupled to the housing; wherein(b) comprises hydraulically actuating the collet connector to releasablycouple the pressure relief device to a mating hub coupled to the subseaconduit.
 13. The method of claim 9, wherein the pressure relief deviceincludes a hot stab coupled to the housing; wherein (b) comprisesinserting the hot stab into a mating receptacle coupled to the subseaconduit.
 14. The method of claim 11, further comprising: (f) ventingfluid from the subsea conduit through the through bore in the housingafter (b) and before (e).
 15. The method of claim 14, furthercomprising: (g) deploying a second pressure relief device subsea,wherein the second pressure relief device includes a housing having aninner cavity and a through bore extending from the inner cavity to anouter surface of the housing, and a burst disc assembly mounted to thehousing within the through bore; (h) coupling the second pressure reliefdevice to the subsea conduit; and (i) providing fluid communicationbetween the inner cavity of the second pressure relief device and thesubsea conduit.
 16. The method of claim 15, wherein (i) comprisesopening a valve in the subsea conduit.
 17. A device for relievingpressure in a subsea fluid conduit, the device comprising: a manifoldincluding an inlet end and a plurality of outlet ends; a connectorcoupled to the inlet end of the manifold, wherein the connector isconfigured to releasably engage a mating connector coupled to the fluidconduit; a plurality of valve spools, wherein each valve spool iscoupled to one of the outlet ends of the manifold, and wherein eachvalve spool includes a valve configure to control a flow of fluidsthrough the corresponding valve spool; a plurality of burst discassemblies, wherein one burst disc assembly is disposed in a throughbore in each valve spool, wherein each burst disc assembly is configuredto rupture at a predetermined differential pressure between the innercavity and the environment outside the housing.
 18. The device of claim17, wherein the valve of each valve spool is positioned between thecorresponding burst disc assembly and the corresponding manifold outletend.
 19. The device of claim 17, wherein each valve spool includes aplurality of through bores, wherein one burst disc assembly is disposedin each through bore.
 20. The device of claim 19, wherein, a first burstdisc assembly coupled to a first valve spool is configured to rupture ata first predetermined pressure differential and a second burst discassembly coupled to a second valve spool is configured to rupture at asecond predetermined pressure differential that is different than thefirst predetermined pressure differential.